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In this study, we analyze the effects of thermal annealing by calculating the optical gain in the InGaN/GaN quantum well. The interdiffusion of Ga and In atoms across the interface of the well and the barrier resulting from thermal treatments is described by Fick’s law. The strong piezoelectric effect due to lattice mismatch in the InGaN/GaN quantum well is also considered in the calculation. The results confirm that the thermal annealing can induce an increase of the optical gain. However, an excessive annealing might result in decreasing the optical gain in the InGaN/GaN quantum well. The maximum optical gain can be obtained at a diffusion length of 4Å of In and Ga atoms. There is a good agreement between the experimental data in literature and the optimized diffusion length studied in this work.

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We propose a novel method to analyze the current-voltage (I-V) characteristics of GaN-based light-emitting diodes (LEDs) with different p-type electrodemesa geometries. The electrical efficiency is analyzed by calculating the electric field under the quasi-coplanar electrodes of GaN-based LEDs. The experimental results for GaN-based LEDs of chip sizes of 350 ϫ 350 m 2 and 1,000 ϫ 1,000 m 2 with interdigitated fingers are compared. A good agreement is obtained between the experimental and theoretical electrical efficiency of the GaN LEDs with a chip size of 1,000 ϫ 1,000 m 2 . The current-crowding effect is analyzed by measuring the electroluminescence spectra of the devices. The result indicates that the current-crowding effect is largely reduced by increasing the number of interdigitated fingers. The electrical efficiency of a LED with a chip size of 1,000 ϫ 1,000 m 2 can be also enhanced by increasing the number of interdigitated fingers, showing the advantages of GaN LED with interdigitated-mesa geometries.